Six-piece optical lens system

ABSTRACT

A six-piece optical lens system includes, in order from the object side to the image side: a stop, a first lens element with a positive refractive power, a second lens element with a negative refractive power, a third lens element with a positive refractive power, a fourth lens element with a negative refractive power, a fifth lens element with a positive refractive power, and a sixth lens element with a negative refractive power. Such arrangements can provide a miniaturized six-piece optical lens system having a big stop and high image quality.

BACKGROUND Field of the Invention

The present invention relates to a six-piece optical lens system, and more particularly to a miniaturized six-piece optical lens system applicable to electronic products.

Description of the Prior Art

In recent years, with the rapid development of portable electronic products, such as, smartphone, tablet computer and so on, small optical lens system applied to portable electronic products has been indispensable. In addition, as the advanced semiconductor manufacturing technologies have allowed the image sensors with smaller size and higher pixel, small optical lens systems have increasingly higher pixel, there's an increasing demand for an optical lens system with better image quality.

Conventional miniaturized optical lens systems used in portable electronic products mostly consist of five lens elements, however, since the high profile portable electronic products, such as smart phone, wearable device and tablet personal computer, are becoming prevalent, the demand for resolution and imaging quality of the miniaturized optical lens systems also increases. The conventional five-piece lens system cannot satisfy higher demand.

Currently, conventional six-piece optical lens systems is developed to provide imaging lens systems with big stop and high image quality, however, the total track length of these optical lens systems is too long, and it is difficult to have the characteristics of big stop, high image quality and miniaturization, which are not applicable to portable electronic products.

The present invention mitigates and/or obviates the aforementioned disadvantages.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a miniaturized six-piece optical lens system having a big stop and high image quality.

Therefore, a six-piece optical lens system in accordance with the present invention comprises, in order from an object side to an image side: a stop; a first lens element with a positive refractive power, having an object-side surface being convex near an optical axis and an image-side surface being concave near the optical axis, at least one of the object-side surface and the image-side surface of the first lens element being aspheric; a second lens element with a negative refractive power, having an object-side surface being convex near the optical axis and an image-side surface being concave near the optical axis, at least one of the object-side surface and the image-side surface of the second lens element being aspheric; a third lens element with a positive refractive power having an object-side surface being convex near the optical axis and an image-side surface being convex near the optical axis, at least one of the object-side surface and the image-side surface of the third lens element being aspheric; a fourth lens element with a negative refractive power having an object-side surface being concave near the optical axis and an image-side surface being convex near the optical axis, at least one of the object-side surface and the image-side surface of the fourth lens element being aspheric; a fifth lens element with a positive refractive power having an object-side surface being convex near the optical axis and an image-side surface being concave near the optical axis, at least one of the object-side surface and the image-side surface of the fifth lens element being aspheric; and a sixth lens element with a negative refractive power having an object-side surface being concave near the optical axis and an image-side surface being convex near the optical axis, at least one of the object-side surface and the image-side surface of the sixth lens element being aspheric and provided with at least one inflection point.

Preferably, a focal length of the first lens element is f1, a focal length of the second lens element is f2, and they satisfy the relation: −0.7<f1/f2<−0.3, so that the refractive power of the first lens element and the second lens element are more suitable, it will be favorable to obtain a wide field of view and avoid the excessive increase of aberration of the system.

Preferably, the focal length of the second lens element is f2, a focal length of the third lens element is f3, and they satisfy the relation: −1.0<f2/f3<−0.6, so that the refractive power of the third lens element can be distributed effectively and will not be too large, it will be favorable to reduce the sensitivity of the system and reduce the aberration.

Preferably, the focal length of the third lens element is f3, a focal length of the fourth lens element is f4, and they satisfy the relation: −1.3<f3/f4<−0.7, so that the refractive power of the fourth lens element can be distributed effectively and will not be too large, it will be favorable to reduce the sensitivity of the system and reduce the aberration.

Preferably, the focal length of the fourth lens element is f4, a focal length of the fifth lens element is f5, and they satisfy the relation: −1.9<f4/f5<−1.3, so that the refractive power of the fifth lens element can be distributed effectively and will not be too large, it will be favorable to reduce the sensitivity of the system and reduce the aberration.

Preferably, the focal length of the fifth lens element is f5, a focal length of the sixth lens element is f6, and they satisfy the relation: −1.4<f5/f6<−0.7, so that the refractive power of the sixth lens element can be distributed effectively and will not be too large, it will be favorable to reduce the sensitivity of the system and reduce the aberration.

Preferably, the focal length of the first lens element is f1, the focal length of the third lens element is f3, and they satisfy the relation: 0.2<f1/f3<0.6, which can balance the refractive power of the six-piece optical lens system, consequently achieving the optimum imaging effect.

Preferably, the focal length of the second lens element is f2, the focal length of the fourth lens element is f4, and they satisfy the relation: 0.6<f2/f4<1.0, which is favorable to increase the field of view and enlarge the stop of the six-piece optical lens system. Meanwhile, the assembling tolerance can be reduced to improve yield rate.

Preferably, the focal length of the third lens element is f3, the focal length of the fifth lens element is f5, and they satisfy the relation: 1.3<f3/f5<2.0, which is favorable to increase the field of view and enlarge the stop of the six-piece optical lens system. Meanwhile, the assembling tolerance can be reduced to improve yield rate.

Preferably, the focal length of the fourth lens element is f4, the focal length of the sixth lens element is f6, and they satisfy the relation: 1.3<f4/f6<2.0, which is favorable to increase the field of view and enlarge the stop of the six-piece optical lens system. Meanwhile, the assembling tolerance can be reduced to improve yield rate.

Preferably, the focal length of the first lens element is f1, a focal length of the second lens element and the third lens element combined is f23, and they satisfy the relation: −0.1<f1/f23<−0.03, which can balance the refractive power of the six-piece optical lens system, consequently achieving the optimum imaging effect.

Preferably, the focal length of the second lens element and the third lens element combined is f23, the focal length of the fourth lens element is f4, and they satisfy the relation: 3.0<f23/f4<7.0, which is favorable to increase the field of view and enlarge the stop of the six-piece optical lens system. Meanwhile, the assembling tolerance can be reduced to improve yield rate.

Preferably, the focal length of the second lens element and the third lens element combined is f23, a focal length of the fourth lens element and the fifth lens element combined is f45, and they satisfy the relation: −5.0<f23/f45<−3.8. If f23/f45 satisfies the above relation, a wide field of view, high pixel and low height can be provided and the resolution can be improved evidently. Contrarily, if f23/f45 exceeds the above range, the performance and resolution of the optical lens system will be reduced, and the yield rate will be low.

Preferably, a focal length of the first lens element and the second lens element combined is f12, a focal length of the third lens element and the fourth lens element combined is f34, and they satisfy the relation: −0.1<f12/f34<−0.03. If f12/f34 satisfies the above relation, a wide field of view, high pixel and low height can be provided and the resolution can be improved evidently. Contrarily, if f12/f34 exceeds the above range, the performance and resolution of the optical lens system will be reduced, and the yield rate will be low.

Preferably, the focal length of the third lens element and the fourth lens element combined is f34, a focal length of the fifth lens element and the sixth lens element combined is f56, and they satisfy the relation: −3.5<f34/f56<−2.3. If f34/f56 satisfies the above relation, a wide field of view, high pixel and low height can be provided and the resolution can be improved evidently. Contrarily, if f34/f56 exceeds the above range, the performance and resolution of the optical lens system will be reduced, and the yield rate will be low.

Preferably, the focal length of the fourth lens element and the fifth lens element combined is f45, the focal length of the sixth lens element is f6, and they satisfy the relation: −2.6<f45/f6<−1.3. If f45/f6 satisfies the above relation, a wide field of view, high pixel and low height can be provided and the resolution can be improved evidently. Contrarily, if f45/f6 exceeds the above range, the performance and resolution of the optical lens system will be reduced, and the yield rate will be low.

Preferably, the focal length of the first lens element is f1, a focal length of the second lens element, the third lens element and the fourth lens element combined is f234, and they satisfy the relation: −0.7<f1/f234<−0.3. Appropriate refractive power is favorable to reduce the spherical aberration and astigmatism of the optical lens system effectively.

Preferably, the focal length of the second lens element, the third lens element and the fourth lens element combined is f234, the focal length of the fifth lens element is f5, and they satisfy the relation: −1.6<f234/f5<−1.0. Appropriate refractive power is favorable to reduce the spherical aberration and astigmatism of the optical lens system effectively.

Preferably, the focal length of the second lens element, the third lens element and the fourth lens element combined is f234, the focal length of the fifth lens element and the sixth lens element combined is f56, and they satisfy the relation: −0.35<f234/f56<−0.05. Appropriate refractive power is favorable to reduce the spherical aberration and astigmatism of the optical lens system effectively.

Preferably, the focal length of the first lens element, the second lens element and the third lens element combined is f123, the focal length of the fourth lens element is f4, and they satisfy the relation: −0.6<f123/f4<−0.2.

Preferably, the focal length of the first lens element, the second lens element and the third lens element combined is f123, the focal length of the fourth lens element and the fifth lens element combined is f45, and they satisfy the relation: 0.15<f123/f45<0.5. If f123/f45 satisfies the above relation, a wide field of view, high pixel and low height can be provided and the resolution can be improved evidently. Contrarily, if f123/f45 exceeds the above range, the performance and resolution of the optical lens system will be reduced, and the yield rate will be low.

Preferably, the focal length of the first lens element, the second lens element and the third lens element combined is f123, the focal length of the fourth lens element, the fifth lens element and the sixth lens element combined is f456, and they satisfy the relation: −0.6<f123/f456<−0.2. If f123/f456 satisfies the above relation, a wide field of view, high pixel and low height can be provided and the resolution can be improved evidently. Contrarily, if f123/f456 exceeds the above range, the performance and resolution of the optical lens system will be reduced, and the yield rate will be low.

Preferably, an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, and they satisfy the relation: 30<V1−V2<42, so that the chromatic aberration of the six-piece optical lens system can be modified effectively.

Preferably, an Abbe number of the third lens element is V3, an Abbe number of the fourth lens element is V4, and they satisfy the relation: 30<V3−V4<42, so that the chromatic aberration of the six-piece optical lens system can be modified effectively.

Preferably, the focal length of the six-piece optical lens system is f, a distance from the object-side surface of the first lens element to the image plane along the optical axis is TL, and they satisfy the relation: 0.6<f/TL<0.95, it will be favorable to obtain a wide field of view and maintain the objective of miniaturization of the six-piece optical lens system, which can be used in thin electronic products.

The present invention will be presented in further details from the following descriptions with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiments in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a six-piece optical lens system in accordance with a first embodiment of the present invention;

FIG. 1B shows the image plane curve and the distortion curve of the first embodiment of the present invention;

FIG. 2A shows a six-piece optical lens system in accordance with a second embodiment of the present invention; and

FIG. 2B shows the image plane curve and the distortion curve of the second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1A and 1B, FIG. 1A shows a six-piece optical lens system in accordance with a first embodiment of the present invention, and FIG. 1B shows, in order from left to right, the image plane curve and the distortion curve of the first embodiment of the present invention. A six-piece optical lens system in accordance with the first embodiment of the present invention comprises a stop 100 and a lens group. The lens group comprises, in order from an object side to an image side: a first lens element 110, a second lens element 120, a third lens element 130, a fourth lens element 140, a fifth lens element 150, a sixth lens element 160, an IR cut filter 170, and an image plane 180, wherein the six-piece optical lens system has a total of six lens elements with refractive power. The stop 100 is disposed between an image-side surface 112 of the first lens element 110 and an object to be imaged.

The first lens element 110 with a positive refractive power has an object-side surface 111 being convex near an optical axis 190 and the image-side surface 112 being concave near the optical axis 190, the object-side surface 111 and the image-side surface 112 are aspheric, and the first lens element 110 is made of plastic material.

The second lens element 120 with a negative refractive power has an object-side surface 121 being convex near the optical axis 190 and an image-side surface 122 being concave near the optical axis 190, the object-side surface 121 and the image-side surface 122 are aspheric, and the second lens element 120 is made of plastic material.

The third lens element 130 with a positive refractive power has an object-side surface 131 being convex near the optical axis 190 and an image-side surface 132 being convex near the optical axis 190, the object-side surface 131 and the image-side surface 132 are aspheric, and the third lens element 130 is made of plastic material.

The fourth lens element 140 with a negative refractive power has an object-side surface 141 being concave near the optical axis 190 and an image-side surface 142 being convex near the optical axis 190, the object-side surface 141 and the image-side surface 142 are aspheric, and the fourth lens element 140 is made of plastic material.

The fifth lens element 150 with a positive refractive power has an object-side surface 151 being convex near the optical axis 190 and an image-side surface 152 being concave near the optical axis 190, the object-side surface 151 and the image-side surface 152 are aspheric, and the fifth lens element 150 is made of plastic material.

The sixth lens element 160 with a negative refractive power has an object-side surface 161 being concave near the optical axis 190 and an image-side surface 162 being convex near the optical axis 190, the object-side surface 161 and the image-side surface 162 are aspheric, the sixth lens element 160 is made of plastic material, and at least one of the object-side surface 161 and the image-side surface 162 is provided with at least one inflection point.

The IR cut filter 170 made of glass is located between the sixth lens element 160 and the image plane 180 and has no influence on the focal length of the six-piece optical lens system.

The equation for the aspheric surface profiles of the respective lens elements of the first embodiment is expressed as follows:

$z = {\frac{{ch}^{2}}{1 + \left\lbrack {1 - {\left( {k + 1} \right)c^{2}h^{2}}} \right\rbrack^{0.5}} + {A\; h^{4}} + {Bh}^{6} + {Ch}^{8} + {Dh}^{10} + {Eh}^{12} + {Gh}^{14} + \ldots}$

wherein:

z represents the value of a reference position with respect to a vertex of the surface of a lens and a position with a height h along the optical axis 190;

c represents a paraxial curvature equal to 1/R (R: a paraxial radius of curvature);

h represents a vertical distance from the point on the curve of the aspheric surface to the optical axis 190;

k represents the conic constant;

A, B, C, D, E, G, . . . : represent the high-order aspheric coefficients.

In the first embodiment of the present six-piece optical lens system, a focal length of the six-piece optical lens system is f, a f-number of the six-piece optical lens system is Fno, the six-piece optical lens system has a maximum view angle (field of view) FOV, and they satisfy the relations: f=3.89 mm; Fno=2.0; and FOV=78 degrees.

In the first embodiment of the present six-piece optical lens system, a focal length of the first lens element 110 is f1, a focal length of the second lens element 120 is f2, and they satisfy the relation: f1/f2=−0.47.

In the first embodiment of the present six-piece optical lens system, the focal length of the second lens element 120 is f2, a focal length of the third lens element 130 is f3, and they satisfy the relation: f2/f3=−0.80.

In the first embodiment of the present six-piece optical lens system, the focal length of the third lens element 130 is f3, a focal length of the fourth lens element 140 is f4, and they satisfy the relation: f3/f4=−1.03.

In the first embodiment of the present six-piece optical lens system, the focal length of the fourth lens element 140 is f4, a focal length of the fifth lens element 150 is f5, and they satisfy the relation: f4/f5=−1.59.

In the first embodiment of the present six-piece optical lens system, the focal length of the fifth lens element 150 is f5, a focal length of the sixth lens element 160 is f6, and they satisfy the relation: f5/f6=−1.08.

In the first embodiment of the present six-piece optical lens system, the focal length of the first lens element 110 is f1, the focal length of the third lens element 130 is f3, and they satisfy the relation: f1/f3=0.37.

In the first embodiment of the present six-piece optical lens system, the focal length of the second lens element 120 is f2, the focal length of the fourth lens element 140 is f4, and they satisfy the relation: f2/f4=0.83.

In the first embodiment of the present six-piece optical lens system, the focal length of the third lens element 130 is f3, the focal length of the fifth lens element 150 is f5, and they satisfy the relation: f3/f5=1.64.

In the first embodiment of the present six-piece optical lens system, the focal length of the fourth lens element 140 is f4, the focal length of the sixth lens element 160 is f6, and they satisfy the relation: f4/f6=1.71.

In the first embodiment of the present six-piece optical lens system, the focal length of the first lens element 110 is f1, a focal length of the second lens element 120 and the third lens element 130 combined is f23, and they satisfy the relation: f1/f23=−0.06.

In the first embodiment of the present six-piece optical lens system, the focal length of the second lens element 120 and the third lens element 130 combined is f23, the focal length of the fourth lens element 140 is f4, and they satisfy the relation: f23/f4=6.06.

In the first embodiment of the present six-piece optical lens system, the focal length of the second lens element 120 and the third lens element 130 combined is f23, a focal length of the fourth lens element 140 and the fifth lens element 150 combined is f45, and they satisfy the relation: f23/f45=−4.58.

In the first embodiment of the present six-piece optical lens system, a focal length of the first lens element 110 and the second lens element 120 combined is f12, a focal length of the third lens element 130 and the fourth lens element 140 combined is f34, and they satisfy the relation: f12/f34=−0.05.

In the first embodiment of the present six-piece optical lens system, the focal length of the third lens element 130 and the fourth lens element 140 combined is f34, a focal length of the fifth lens element 150 and the sixth lens element 160 combined is f56, and they satisfy the relation: f34/f56=−2.69.

In the first embodiment of the present six-piece optical lens system, the focal length of the fourth lens element 140 and the fifth lens element 150 combined is f45, the focal length of the sixth lens element 160 is f6, and they satisfy the relation: f45/f6=−2.26.

In the first embodiment of the present six-piece optical lens system, the focal length of the first lens element 110 is f1, a focal length of the second lens element 120, the third lens element 130 and the fourth lens element 140 combined is f234, and they satisfy the relation: f1/f234=−0.48.

In the first embodiment of the present six-piece optical lens system, the focal length of the second lens element 120, the third lens element 130 and the fourth lens element 140 combined is f234, the focal length of the fifth lens element 150 is f5, and they satisfy the relation: f234/f5=−1.29.

In the first embodiment of the present six-piece optical lens system, the focal length of the second lens element 120, the third lens element 130 and the fourth lens element 140 combined is f234, the focal length of the fifth lens element 150 and the sixth lens element 160 combined is f56, and they satisfy the relation: f234/f56=−0.17.

In the first embodiment of the present six-piece optical lens system, a focal length of the first lens element 110, the second lens element 120 and the third lens element 130 combined is f123, the focal length of the fourth lens element 140 is f4, and they satisfy the relation: f123/f4=−0.43.

In the first embodiment of the present six-piece optical lens system, the focal length of the first lens element 110, the second lens element 120 and the third lens element 130 combined is f123, the focal length of the fourth lens element 140 and the fifth lens element 150 combined is f45, and they satisfy the relation: f123/f45=0.33.

In the first embodiment of the present six-piece optical lens system, the focal length of the first lens element 110, the second lens element 120 and the third lens element 130 combined is f123, a focal length of the fourth lens element 140, the fifth lens element 150 and the sixth lens element 160 combined is f456, f123/f456=−0.42.

In the first embodiment of the present six-piece optical lens system, an Abbe number of the first lens element 110 is V1, an Abbe number of the second lens element 120 is V2, and they satisfy the relation: V1−V2=34.5.

In the first embodiment of the present six-piece optical lens system, an Abbe number of the third lens element 130 is V3, an Abbe number of the fourth lens element 140 is V4, and they satisfy the relation: V3−V4=34.5.

In the first embodiment of the present six-piece optical lens system, the focal length of the six-piece optical lens system is f, a distance from the object-side surface 111 of the first lens element 110 to the image plane 180 along the optical axis 190 is TL, and they satisfy the relation: f/TL=0.85.

The detailed optical data of the first embodiment is shown in table 1, and the aspheric surface data is shown in table 2.

TABLE 1 Embodiment 1 f(focal length) = 3.89 mm, Fno = 2.0, FOV = 78 deg. surface Curvature Radius Thickness Material Index Abbe # Focal length 0 object infinity infinity 1 infinity 0.300 2 stop infinity −0.300  3 Lens 1 1.421 (ASP) 0.629 plastic 1.544 56.000 3.012 4 8.800 (ASP) 0.105 5 Lens 2 13.326 (ASP) 0.239 plastic 1.651 21.500 −6.447 6 3.196 (ASP) 0.324 7 Lens 3 56.461 (ASP) 0.375 plastic 1.544 56.000 8.047 8 −4.757 (ASP) 0.342 9 Lens 4 −0.933 (ASP) 0.302 plastic 1.651 21.500 −7.790 10 −1.287 (ASP) 0.054 11 Lens 5 1.594 (ASP) 0.496 plastic 1.544 56.000 4.899 12 3.509 (ASP) 0.402 13 Lens 6 −2.437 (ASP) 0.352 plastic 1.535 56.000 −4.556 14 −531.535 (ASP) 0.307 15 IR-filter infinity 0.300 glass 1.517 64.167 — 16 infinity 0.350 17 Image plane infinity infinity

TABLE 2 Aspheric Coefficients surface 3 4 5 6 7 8 K: −2.1156E−01  1.9788E+01  1.9960E+02 −2.3973E+01 −2.0005E+02  9.1747E+00 A:  1.8400E−02 −1.3383E−01 −1.8482E−01 −1.0924E−02 −1.6042E−01 −8.4133E−02 B: −1.0375E−01  3.3723E−01  3.5010E−01  3.4261E−01 −8.2262E−02  5.0657E−02 C:  4.5840E−01 −1.4023E+00 −2.9659E−01 −9.5442E−01  1.1973E−01 −4.8933E−01 D: −1.1060E+00  4.3185E+00  3.6527E−01  3.0474E+00 −4.6005E−01  1.2412E+00 E:  1.4320E+00 −7.9438E+00 −1.1238E+00 −5.9281E+00  1.1688E+00 −1.5349E+00 F: −9.5950E−01  7.5364E+00  1.7295E+00  6.0047E+00 −1.8692E+00  9.4097E−01 G:  2.3674E−01 −2.8762E+00 −9.0914E−01 −2.2048E+00  1.3536E+00 −1.9431E−01 surface 9 10 11 12 13 14 K: −3.8672E+00 −8.2613E−01 −1.0420E+01 −9.6324E+00 −3.9509E−02 −1.2936E+03 A:  5.3042E−02  6.7135E−02 −8.5886E−02  7.3665E−03  1.0270E−01  2.7623E−02 B: −3.1856E−01 −7.0244E−02 −6.4647E−02 −1.9310E−01 −2.2580E−01 −1.1711E−01 C:  5.5836E−01  1.2369E−01  9.1343E−02  1.9947E−01  1.6222E−01  8.4440E−02 D: −2.9469E−01 −3.6117E−02 −6.8859E−02 −1.3122E−01 −5.4691E−02 −2.9048E−02 E: −6.1208E−02 −1.0500E−02  2.1715E−02  5.1044E−02  9.9585E−03  5.2326E−03 F:  1.1252E−01  3.8368E−03 −1.3719E−03 −1.0271E−02 −9.5224E−04 −4.7377E−04 G: −3.2462E−02  4.5103E−06 −2.5702E−04  8.2595E−04  3.7866E−05  1.7037E−05

The units of the radius of curvature, the thickness and the focal length in table 1 are expressed in mm, the surface numbers 0-17 represent the surfaces sequentially arranged from the object-side to the image-side along the optical axis. In table 2, k represents the conic coefficient of the equation of the aspheric surface profiles, and A, B, C, D, E, F . . . : represent the high-order aspheric coefficients. The tables presented below for each embodiment are the corresponding schematic parameter and image plane curves, and the definitions of the tables are the same as Table 1 and Table 2 of the first embodiment. Therefore, an explanation in this regard will not be provided again.

Referring to FIGS. 2A and 2B, FIG. 2A shows a six-piece optical lens system in accordance with a second embodiment of the present invention, and FIG. 2B shows, in order from left to right, the image plane curve and the distortion curve of the second embodiment of the present invention. A six-piece optical lens system in accordance with the second embodiment of the present invention comprises a stop 200 and a lens group. The lens group comprises, in order from an object side to an image side: a first lens element 210, a second lens element 220, a third lens element 230, a fourth lens element 240, a fifth lens element 250, a sixth lens element 260, an IR cut filter 270, and an image plane 280, wherein the six-piece optical lens system has a total of six lens elements with refractive power. The stop 200 is disposed between an image-side surface 212 of the first lens element 210 and an object to be imaged.

The first lens element 210 with a positive refractive power has an object-side surface 211 being convex near an optical axis 290 and the image-side surface 212 being concave near the optical axis 290, the object-side surface 211 and the image-side surface 212 are aspheric, and the first lens element 210 is made of plastic material.

The second lens element 220 with a negative refractive power has an object-side surface 221 being convex near the optical axis 290 and an image-side surface 222 being concave near the optical axis 290, the object-side surface 221 and the image-side surface 222 are aspheric, and the second lens element 220 is made of plastic material.

The third lens element 230 with a positive refractive power has an object-side surface 231 being convex near the optical axis 290 and an image-side surface 232 being convex near the optical axis 290, the object-side surface 231 and the image-side surface 232 are aspheric, and the third lens element 230 is made of plastic material.

The fourth lens element 240 with a negative refractive power has an object-side surface 241 being concave near the optical axis 290 and an image-side surface 242 being convex near the optical axis 290, the object-side surface 241 and the image-side surface 242 are aspheric, and the fourth lens element 240 is made of plastic material.

The fifth lens element 250 with a positive refractive power has an object-side surface 251 being convex near the optical axis 290 and an image-side surface 252 being concave near the optical axis 290, the object-side surface 251 and the image-side surface 252 are aspheric, and the fifth lens element 250 is made of plastic material.

The sixth lens element 260 with a negative refractive power has an object-side surface 261 being concave near the optical axis 290 and an image-side surface 262 being convex near the optical axis 290, the object-side surface 261 and the image-side surface 262 are aspheric, the sixth lens element 260 is made of plastic material, and at least one of the object-side surface 261 and the image-side surface 262 is provided with at least one inflection point.

The IR cut filter 270 made of glass is located between the sixth lens element 260 and the image plane 280 and has no influence on the focal length of the six-piece optical lens system.

The detailed optical data of the second embodiment is shown in table 3, and the aspheric surface data is shown in table 4.

TABLE 3 Embodiment 2 f(focal length) = 3.88 mm, Fno = 2.0, FOV = 79 deg. surface Curvature Radius Thickness Material Index Abbe # Focal length 0 object infinity infinity 1 infinity 0.327 2 stop infinity −0.327  3 Lens 1 1.423 (ASP) 0.629 plastic 1.544 56.000 3.015 4 8.844 (ASP) 0.105 5 Lens 2 13.342 (ASP) 0.240 plastic 1.651 21.500 −6.430 6 3.191 (ASP) 0.321 7 Lens 3 76.456 (ASP) 0.375 plastic 1.544 56.000 8.123 8 −4.704 (ASP) 0.340 9 Lens 4 −0.935 (ASP) 0.300 plastic 1.651 21.500 −7.756 10 −1.290 (ASP) 0.054 11 Lens 5 1.598 (ASP) 0.505 plastic 1.544 56.000 4.890 12 3.532 (ASP) 0.397 13 Lens 6 −2.441 (ASP) 0.351 plastic 1.535 56.000 −4.819 14 −44.788 (ASP) 0.350 15 IR-filter infinity 0.300 glass 1.517 64.167 — 16 infinity 0.314 17 Image plane infinity infinity

TABLE 4 Aspheric Coefficients surface 3 4 5 6 7 8 K: −2.1068E−01  2.0422E+01  2.0000E+02 −2.3869E+01 −2.0000E+02  9.2746E+00 A:  1.8456E−02 −1.3366E−01 −1.8491E−01 −1.1020E−02 −1.6041E−01 −8.4559E−02 B: −1.0364E−01  3.3693E−01  3.5028E−01  3.4179E−01 −8.1879E−02  5.0537E−02 C:  4.5838E−01 −1.4034E+00 −2.9639E−01 −9.5536E−01  1.1847E−01 −4.8834E−01 D: −1.1063E+00  4.3167E+00  3.6460E−01  3.0478E+00 −4.6313E−01  1.2425E+00 E:  1.4314E+00 −7.9455E+00 −1.1263E+00 −5.9263E+00  1.1656E+00 −1.5340E+00 F: −9.6001E−01  7.5364E+00  1.7259E+00  6.0032E+00 −1.8689E+00  9.4117E−01 G:  2.3708E−01 −2.8720E+00 −9.0811E−01 −2.2223E+00  1.3601E+00 −1.9481E−01 surface 9 10 11 12 13 14 K: −3.8492E+00 −8.1860E−01 −1.0326E+01 −9.6924E+00 −3.8076E−02 −8.2970E+04 A:  5.3620E−02  6.6518E−02 −8.5750E−02  6.5469E−03  1.0197E−01  2.9142E−02 B: −3.1810E−01 −7.0297E−02 −6.4731E−02 −1.9336E−01 −2.2577E−01 −1.1730E−01 C:  5.5834E−01  1.2388E−01  9.1308E−02  1.9941E−01  1.6223E−01  8.4428E−02 D: −2.9473E−01 −3.6020E−02 −6.8868E−02 −1.3123E−01 −5.4690E−02 −2.9048E−02 E: −6.1125E−02 −1.0475E−02  2.1713E−02  5.1045E−02  9.9586E−03  5.2327E−03 F:  1.1268E−01  3.8370E−03 −1.3723E−03 −1.0270E−02 −9.5227E−04 −4.7375E−04 G: −3.2276E−02  4.5103E−06 −2.5691E−04  8.2612E−04  3.7854E−05  1.7039E−05

In the second embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the first embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the first embodiment with corresponding values for the second embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 3 and Table 4 as the following values and satisfy the following conditions:

Embodiment 2 f [mm] 3.88 f23/f45 −4.24 Fno 2.0 f12/f34 −0.05 FOV [deg.] 79 f34/f56 −3.15 f1/f2 −0.47 f45/f6 −2.15 f2/f3 −0.79 f1/f234 −0.48 f3/f4 −1.05 f234/f5 −1.27 f4/f5 −1.59 f234/f56 −0.23 f5/f6 −1.01 f123/f4 −0.44 f1/f3 0.37 f123/f45 0.33 f2/f4 0.83 f123/f456 −0.39 f3/f5 1.66 V1-V2 34.5 f4/f6 1.61 V3-V4 34.5 f1/f23 −0.07 f/TL 0.85 f23/f4 5.66

In the present six-piece optical lens system, the lens elements can be made of plastic or glass. If the lens elements are made of plastic, the cost will be effectively reduced. If the lens elements are made of glass, there is more freedom in distributing the refractive power of the six-piece optical lens system. Plastic lens elements can have aspheric surfaces, which allow more design parameter freedom (than spherical surfaces), so as to reduce the aberration and the number of the lens elements, as well as the total track length of the six-piece optical lens system.

In the present six-piece optical lens system, if the object-side or the image-side surface of the lens elements with refractive power is convex and the location of the convex surface is not defined, the object-side or the image-side surface of the lens elements near the optical axis is convex. If the object-side or the image-side surface of the lens elements is concave and the location of the concave surface is not defined, the object-side or the image-side surface of the lens elements near the optical axis is concave.

The six-piece optical lens system of the present invention can be used in focusing optical systems and can obtain better image quality. The six-piece optical lens system of the present invention can also be used in electronic imaging systems, such as, 3D image capturing, digital camera, mobile device, digital flat panel or vehicle camera.

While we have shown and described various embodiments in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention. 

What is claimed is:
 1. A six-piece optical lens system, in order from an object side to an image side, comprising: a stop; a first lens element with a positive refractive power, having an object-side surface being convex near an optical axis and an image-side surface being concave near the optical axis, at least one of the object-side surface and the image-side surface of the first lens element being aspheric; a second lens element with a negative refractive power, having an object-side surface being convex near the optical axis and an image-side surface being concave near the optical axis, at least one of the object-side surface and the image-side surface of the second lens element being aspheric; and a third lens element with a positive refractive power, having an object-side surface being convex near the optical axis an image-side surface being convex near the optical axis, at least one of the object-side surface and the image-side surface of the third lens element being aspheric; a fourth lens element with a negative refractive power, having an object-side surface being concave near the optical axis an image-side surface being convex near the optical axis, at least one of the object-side surface and the image-side surface of the fourth lens element being aspheric; a fifth lens element with a positive refractive power, having an object-side surface being convex near the optical axis an image-side surface being concave near the optical axis, at least one of the object-side surface and the image-side surface of the fifth lens element being aspheric; and a sixth lens element with a negative refractive power, having an object-side surface being concave near the optical axis an image-side surface being convex near the optical axis, at least one of the object-side surface and the image-side surface of the sixth lens element being aspheric; and the sixth lens element is provided with at least one inflection point; wherein the lens system has a total of six lens elements, a focal length of the third lens element is f3, a focal length of the fourth lens element is f4, and they satisfy the relation: −1.3<f3/f4<−0.7.
 2. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the first lens element is f1, a focal length of the second lens element is f2, and they satisfy the relation: −0.7<f1/f2<−0.3.
 3. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the second lens element is f2, the focal length of the third lens element is f3, and they satisfy the relation: −1.0<f2/f3<−0.6.
 4. The six-piece optical lens system as claimed in claim 1, wherein the focal length of the fourth lens element is f4, a focal length of the fifth lens element is f5, and they satisfy the relation: −1.9<f4/f5<−1.3.
 5. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the fifth lens element is f5, a focal length of the sixth lens element is f6, and they satisfy the relation: −1.4<f5/f6<−0.7.
 6. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the first lens element is f1, the focal length of the third lens element is f3, and they satisfy the relation: 0.2<f1/f3<0.6.
 7. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the second lens element is f2, the focal length of the fourth lens element is f4, and they satisfy the relation: 0.6<f2/f4<1.0.
 8. The six-piece optical lens system as claimed in claim 1, wherein the focal length of the third lens element is f3, a focal length of the fifth lens element is f5, and they satisfy the relation: 1.3<f3/f5<2.0.
 9. The six-piece optical lens system as claimed in claim 1, wherein the focal length of the fourth lens element is f4, a focal length of the sixth lens element is f6, and they satisfy the relation: 1.3<f4/f6<2.0.
 10. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the first lens element is f1, a focal length of the second lens element and the third lens element combined is f23, and they satisfy the relation: −0.1<f1/f23<−0.03.
 11. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the second lens element and the third lens element combined is f23, the focal length of the fourth lens element is f4, and they satisfy the relation: 3.0<f23/f4<7.0.
 12. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the second lens element and the third lens element combined is f23, a focal length of the fourth lens element and the fifth lens element combined is f45, and they satisfy the relation: −5.0<f23/f45<−3.8.
 13. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the first lens element and the second lens element combined is f12, a focal length of the third lens element and the fourth lens element combined is f34, and they satisfy the relation: −0.1<f12/f34<−0.03.
 14. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the third lens element and the fourth lens element combined is f34, a focal length of the fifth lens element and the sixth lens element combined is f56, and they satisfy the relation: −3.5<f34/f56<−2.3.
 15. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the fourth lens element and the fifth lens element combined is f45, a focal length of the sixth lens element is f6, and they satisfy the relation: −2.6<f45/f6<−1.3.
 16. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the first lens element is f1, a focal length of the second lens element, the third lens element and the fourth lens element combined is f234, and they satisfy the relation: −0.7<f1/f234<−0.3.
 17. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the second lens element, the third lens element and the fourth lens element combined is f234, a focal length of the fifth lens element is f5, and they satisfy the relation: −1.6<f234/f5<−1.0.
 18. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the second lens element, the third lens element and the fourth lens element combined is f234, a focal length of the fifth lens element and the sixth lens element combined is f56, and they satisfy the relation: −0.35<f234/f56<−0.05.
 19. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the first lens element, the second lens element and the third lens element combined is f123, the focal length of the fourth lens element is f4, and they satisfy the relation: −0.6<f123/f4<−0.2.
 20. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the first lens element, the second lens element and the third lens element combined is f123, a focal length of the fourth lens element and the fifth lens element combined is f45, and they satisfy the relation: 0.15<f123/f45<0.5.
 21. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the first lens element, the second lens element and the third lens element combined is f123, a focal length of the fourth lens element, the fifth lens element and the sixth lens element combined is f456, and they satisfy the relation: −0.6<f123/f456<−0.2.
 22. The six-piece optical lens system as claimed in claim 1, wherein an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, and they satisfy the relation: 30<V1−V2<42.
 23. The six-piece optical lens system as claimed in claim 1, wherein an Abbe number of the third lens element is V3, an Abbe number of the fourth lens element is V4, and they satisfy the relation: 30<V3−V4<42.
 24. The six-piece optical lens system as claimed in claim 1, wherein a focal length of the six-piece optical lens system is f, a distance from the object-side surface of the first lens element to an image plane along the optical axis is TL, and they satisfy the relation: 0.6<f/TL<0.95. 